Spring base for upholstered seat backs



y 5, 1954 R. o. lsAAcs 3,131,924

SPRING BASE FOR UPHOLSTERED SEAT BACKS Filed Aug. 9, 1962 3b 28 f0 1 321 .7416 3a .24 y 4042 INVENTOR. fimwa L220.

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United States Patent O 3,131,924 SPRING BASE FOR UPI-IGLSTERED SEATBACKS Robert 0. Isaaes, Joplin, Mo., assignor to Flex-O-Lators, Inc.,Carthage, Mo., a corporation of Missouri Fiied Aug. 9, 1952, Ser. No.215,844 7 Claims. (Cl. 267-107) This invention relates to new and usefulimprovements in upholstered, spring-based furniture, and has particularreference to a spring base particularly adapted for use in seat backs.

Among the main objects of the present invention is the provision of aspring base which is quite firm and will hold its form through longperiods of hard usage, so as to preserve the padding and upholsterylayers applied thereover in a neat, tailored appearance, but whichnevertheless possesses the softness and yieldability quite adequate forcomfort. The upper edge of the base is a soft edge for comfort, that is,it will yield rearwardly, but is supported in a novel manner withsuflicient firmness to prevent sagging, or the assumption of an unevenor undulating line even after long periods of usage. Provision is alsomade for preventing lateral movement of the upper edge of the base. Thebase structure involves spring strips more or less rigidly fixed attheir upper and lower ends, and having their intermediate portions bowedforwardly. This type of structure, which is in common usage in seatbacks, has a common fault in that as said strips are deflectedrearwardly by the pressure of a persons back to a rearwardly bowedposition, they tend to snap, or change their direction of bowing verysuddenly as they pass between their upper and lower supports. Thissnap-action causes a disconcerting, uncomfortable sensation. The presentstructure has novel means for overcoming this fault.

Another object is the provision of a spring base of the characterdescribed which is adapted to be supplied to furniture manufacturers asa completely integrated unit not requiring any additional assembly, andwhich may be mounted in a furniture frame with the least possible timeand labor, and with no tools or implements other than hammer and nails.Before mounting in the furniture frame, the base may be collapsed intoan extremely compact form for greater convenience and economy ofstorage, handling and shipping.

A further object is the provision of a spring base of the characterdescribed having a novel means for providing additional support for thelower portion of a persons back, thereby encouraging better seatingposture and reducing fatigue.

Other objects are simplicity and economy of construction, efliciency anddependability of operation, and adaptability for use in furniture of awide variety of styles and types.

With these objects in view, as well as other objects which will appearin the course of the specification, reference will be had to theaccompanying drawings, wherein:

FIG. 1 is a front elevational view of the back portion of a furnitureseating frame, showing a spring base embodying the present inventionmounted therein, with the padding and upholstery layers omitted,

FIG. 2 is a sectional view taken on line HII of FIG. 1, indicating theseat cushion in dotted lines, and

FIG. 3 is a view of the spring base only, separated from the furnitureframe and collapsed for shipping or storage.

Like reference numerals apply to similar parts throughout the severalviews, and the numeral 2 applies generally to the back frame of afurniture piece such as an up holstered chair, couch, sofa or the like,a chair being shown for the purposes of illustration. The remainder ofthe frame, such as the seat, legs and arms, is not pertinent 3,131,924Patented May 5, 1964 to the present invention and is not shown. Saidframe comprises a pair of side uprights 4 connected at their upper rearportions by ahorizontal cross bar 6, at their lower rear portions by ahorizontal cross bar 8, and at their lower forward portions by ahorizontal cross bar 10. Said uprights and cross bars are formed of woodor other suitable material, and are rigidly connected to form a rigid,unitary structure. In the particular embodiment illustrated, the upperportions of uprights 4 are provided with outward offsets forming wings12 which in the finished chair will overlie the upper surfaces of thechair arms.

The spring base forming the subject matter of the present invention isindicated generally by the numeral 14, and includes a plurality ofcompound spring units (five illustrated) each indicated generally by thenumeral 16. Each of said units comprises a vertically extending springsteel strip 18 arranged to flex forwardly and rearwardly and fixed atits lower end to frame cross bar 10 as by a nail 20, and a generallyS-shaped auxiliary spring strip 22 (see FIG. 2) alfixed at one end toend of strip 18, adjacent the upper end thereof, by a pair of rivets 24.From its point of attachment to strip 18, strip 22 is curved rearwardlyand downwardly, then upwardly, and is affixed at its opposite end toframe cross bar 6, as by a nail 26. The upper end portions of strips 18are thus normally supported well forwardly of cross bar 6, so as to berearwardly yieldable, and strips 18 are flexed in a forwardly bowedposition as shown in FIG. 2. The spring units 16 are disposed generallyin regularly spaced relation across the Width of the chair, as indicatedin FIG. 1. A greater or smaller number of units could be used, asnecessary or desired. 7

The upper ends of strips 18 are joined by a series of short connectors28, 3t), 32 and 34, each formed of a length of spring steel strip. Eachof said connectors extends between and overlaps the upper ends of asuccessive pair of strips 18, and the overlapping contiguous ends ofeach successive pair of connectors are pivoted to the associated strip18 by a rivet 36. The sidemost connectors 28 and 34 are extendedoutwardly from the associated strips 18, and each has a hole 38 formedin the extended portion thereof. One end of a tension spring 40 'issecured in each of holes 38. Said springs extend laterally outwardly andrearwardly, and each is secured at its outer end to a nail 42 driveninto the upper end of the associated frame upright 4. The intermediateportions of spring strips 18 are joined by a continuous spring steelconnector strip 44 which extends horizontally, being pivoted to each ofstrips 18 at its point of intersection therewith by a rivet 46.Intermediate connector 44 and the lower ends of strips 18, each strip 18has an S-bend 48 formed therein and lying generally in the same verticalplane as strips 13 and 2-2 of the spring unit. Said S-bend provides aforward to rearward offset, so that the portion of strip 18 below thebend is offset rearwardly from the portion above the bend. The purposeof these S-bends will bediscussed presently. It will be understood thatframe 2 and spring base 14 will in actual use be covered by upholsterymaterial such as spring insulation, padding and decorative fabric, butthat these layers have been omitted from the drawing for purposes ofclarity.

In use, it will be seen that as a person leans rearwardly against theback, the strips 18 will be flexed from the forwardly bowed positionshown in FIG. 2 to a rearwardly bowed position, in addition to a generalrearward movement provided by compression of the s-shaped auxiliarysprings 22. In moving from a forwardly to a rearwardly ward avrearwardly bowed position. If the distance between the upper and lowerends of strips 18 were fixed, as if both ends were afiixed to frame 2,then the strips would be forced into an S-bend as they passed betweenthe Supports, and would snap to their rearwardly bowed positions. Thissnap action, previously discussed, is highly objectionable. In the,present'structure, the connection between the upper ends of strips 18formed by connector links 28, 30, 32 and 34 is free to move upwardly asstrips 18 lengthen, so that the strips may move freely and smoothly fromforwardly to rearwardly bowed position with no snap action. S-shapedauxiliary springs 22 of course do not interfere appreciably withvertical movement of the upper ends of strips 18.

' However, if connections 28, 30, 32 and 34 were a continuous memberrather than pivoted links as shown, snap action could occur, since apersons weight is seldom if ever applied uniformly across the entirewidth of a chair back, but is concentrated more heavily at one part ofthe chair width. Hence strips 18 must lengthen unequally as they areflexed, and those strips which must lengthen to a greater extent, beingrestricted by the top connector, which is in turn restricted by strips18 which are not lengthened to the same degree, would still have a snapaction. In the present structure, the snap action due to unequallengthening of strips 18 is prevented by'relative pivoting of connectorlinks 28, 30, 32 and 34. That is, if one strip 18 tends to lengthen morethan those adjacentto it, upper end is freed .to move upwardly toa'gre-ater extent by pivotal movement'of. the adjacent links, asindicated in dotted lines at 30' and 32"in FIG. 1, although it isexaggerated in the drawing for clarity. Relative pivoting of the linksoccurs to some degree every time the seat back is flexed, and while suchpivoting does draw the upper ends of strips 18 somewhat closer together,the movement is so slight as to be almost imperceptible, and in anyevent is rendered quite easy by the free lateral movement of 18 whichresults from springs 40 and. springs 22.

Therelative pivoting of connector links 28, 30, 32 and 34' could resultin permanent angular relation thereof due to gradual deformation ofstrips 1 8 over long periods of usage, and since said connectorlinks'form the padding support for the upper edge of the cushion, suchpermanent anglingpof the connector would result in a sagging,undulating, uneven, or otherwise unsightly edge, were it not for springs40. These springs maintain the-chain formed by links 28, 30, 32 and 34under constant tension and hence normally straight. Thus a neat,tailored edge is retained even after long, hard usage. Springs 40 alsofunction to prevent to a great degree any general lateral movement ofside sway of the upper portion of the springbase.

The S-bends 48 of strips 18 are disposed preferably at or above theseating level of the chair, as indicated by the seat cushion 50 shown indotted lines in FIG. 2. It will be understood that said cushion iscompressible, and is itself supported on a spring base, not shown. Hencewhen a person sits in the .chair, the S-bend 48 forms a rearward offset,overlaid by padding of course, which engages the persons back somewhatabove the bottom of his hips. This provides a posture chair in that thepersons hips may move somewhat rearwardly beneath the S-bend, andadditional support is provided for the lower back. This reduces fatigue,and is conducive to better posture. The actual elevation of bends 48 isof course subject to variation as deemed advisable. An S-bend has beenfound to be preferable to a .contoured strip 18 wherein the strip iscurved to an actual theoretical curve of the humanspine, or to any typeof angular offset, since the S-bend maintains the entire length of thestrip in a virtually pure bending stress as it is flexed in use, while acontoured or angularlyoffset strip creates zones of stress concentrationleading to early failure. On standard furniture machines the back shownwithstood up 4 to five and six more flexings with the S-bend,.beforefailure, as the same back contoured or angularly offset springs 18.

S bends 48 are also useful in connection with the lengthening action of18 as described in connection with links 28, 30, 32 and 34. Firstly, theS-bends do permit some degree of relative vertical movement between theportions of the strip above and below the bend. This permits ashortening of the strips 18 to offset partially the total lengtheningrequired, so that less movement of 28, 30, 32 and 34 is required.Secondly, S-bends 48 permit shortening of the strips 18 between theirlower ends and continuous connector strip 44. Said connector strip isdesirable, to maintain proper spacing of strips 18 and to provide bettergeneral stability of the structure, but nevertheless does inhibitrelative vertical movement of the strips 18 and could permit snap actionof the lower portions of strips 18, if it were not for bends 48. I V

As shown in 'FIG. 3, the spring base 14, when it is separated from theframe, may be collapsed or folded into a very compact form with springunits lying in contacting relation in parallel planes, due to thepivotal action supplied by rivets 36 and 46. This greatly reduces thebulk of the spring base, and constitutes a great advantage when storing,shipping or handling said bases, in that a much greater number of themmay be packed into a small space. Assembled spring decks or bases of thegeneral type shown are notoriously inconvenient to ship and store, dueto their extremely large bulk as compared to their weight. This expensehas made it necessary in many instances to sell and ship spring bases ina knockeddown or disassembled condition, so that assembly and mountingthereof was a tedious and expensive procedure for the furnituremanufacturer utilizing them. The present base may feasibly andeconomically be furnished in completely assembled form, and may bemounted quickly and easily with only a hammer and nails.

While I have shown and described a specific embodiment of my invention,it be readily apparent that many minor changes of structure andoperation could be made without departing from the spirit of theinvention as defined by the scope of the appended claims.

What I claim as new and desire to protect by Letters Patent is:

1. In combination: (a) -a furniture seat including a back frame havingrigidly associated top and bottom horizontal cross bars, and (b) aspring base mounted in said back frame and comprising:

(1) a plurality of upright spring strips spaced regularly across saidframe and each affixed at its lower end to said bottom cross bar andextending upwardly therefirom, the intermediate portion of each stripbeing normally bowed forwardly and the upper end thereof being spacedapart forwardly from said top cross bar,

(2) a compressible auxiliary spring element secured at its forward endto each of said upright stripsradjacent the upper end thereof, andsecured at its rearwardend to said top cross bar, and

(3) a horizontal cross strip extending across said spring base at theupper ends of said upright strips and comprising a series of links offlat spring material, each successive pair of said links being connectedpivotally together, and to the upper end of one of said upright strips,on an axis normal to the general plane established by said upright p 2.The combination as recited in claim 1 with the addition of:

(a) resilient means biasing said links toward a straight,

aligned relation.

3. The combination as recited in claim 1 with the addition of:

(a) resilient means tensioning said cross strip longitudinally, wherebythe thereof are biased yieldably toward a straight, aligned relation.

4. The combination as recited in claim 1 with the addition of:

(a) a pair of tension springs secured respeotively to opposite ends ofsaid cross-strip, said springs extending longitudinally outwardly fromthe ends of said cross strip and being secured at their outer ends tosaid frame, whereby said cross strip is tensione-d.

5. The combination as recited in elm 1 wherein each of said uprightstrips is formed in an S-shape at or immediately above the seating levelof said seat, so that the portion of the strip below said S-shape isofiset rearwardly item the portion thereof above said S-shape.

6. The combination as recited in claim 1 wherein each of said uprightstrips is formed in an S-shape at or immediately above the seat ng levelof said seat, so that the pontion of the strip below said S-shape isoffset rearwardly firorn the portion thereof above said $-shape, andwith the addition of:

(a) a continuous horizontal cross strip extending across said springbase and being secured to each of said upright strips at a pointintermediate the S-shape thereof and said first-named top cross strip.

7. The combination as recited in claim 6 wherein said continuous crossship is pivoted to each of said upright strips on an axis parallel tothe pivotal connection of said linked across srtm'p thereto, wherebywhen said spring base is separated Tom said firame, the former may befolded so that said upright strips are disposed in parallel, abuttingrelation.

Ball Mar. 17, 1936 Flint Apr. 30, 1957

1. IN COMBINATION: (A) A FURNITURE SEAT INCLUDING A BACK FRAME HAVINGRIDGIDLY ASSOCIATED TO AND BOTTOMM HORIZONTAL CROSS BAR, AND (B) ASPRING BASE MOUNTED IN SAID BACK FRAME AND COMPRISING: (1) A PLURALITYOF UPRIGHT SPRING STRIPS SPACED REGULARLY ACROSS SAID FRAME AND EACHAFFIXED AT ITS LOWER END TO SAID BOTTOM CROSS BAR AND EXTENDING UPWARDLYTHEREFROM, THE INTERMEDIATE PORTION OF EACH STRIP BEING NORMALLY BOWEDFORWARDLY AND THE UPPER END THEREOF BEING SPACED APART FORWARDLY FROMSAID TOP CROSS BAR, (2) A COMPRESSIBLE AUXILIARY SPRING ELEMENT SECUREDAT ITS FORWARD END TO EACH OF SAID UPRIGHT STRIPS ADJACENT THE UPPER ENDTHEREOF, AND SECURED AT ITS REARWARD END TO SAID TOP CROSS BAR, AND (3)A HORIZONTAL CROSS STRIP EXTENDING ACROSS SAID SPRING BASE AT THE UPPERENDS OF SAID UPRIGHT STRIPS AND COMPRISING A SERIES OF LINKS OF FLATSPRING MATERIAL, EACH SUCCESSIVE PAIR OF SAID LINKS BEING CONNECTEDPIVOTALLY TOGETHER, AND TO THE UPPER END OF ONE OF SAID UPRIGHT STRIPS,ON AN AXIS NORMAL TO THE GENERAL PLANE ESTABLISHED BY SAID UPRIGHTSTRIPS.